Many high-end lighting applications require a plurality of luminaires aimed at an area of given size to generate a predefined illumination pattern on the area. Examples of such applications include arena lighting systems for illuminating sports arenas, e.g. field, pitch or stadium lighting, façade lighting, shop floor lighting, parking lot lighting and so on. The desired predefined illumination pattern may be a uniform or homogenous lighting pattern.
A light designer may be employed to create a so-called lighting plan for the area to be illuminated, in which the light designer determines the mounting positions of the luminaires relative to the area to be illuminated and the aiming information for the luminaires, e.g. in which orientation the luminaires are to be mounted such that the luminaires can cooperate to generate the predefined illumination pattern. The light plan may contain, for each luminaire, information such as the type of luminaire, the mounting location and orientation of the luminaire, and the aiming location or point, e.g. relative to the centre of the area to be illuminated. For example, a football stadium may have a lighting plan or design where the lighting system contains more than 100 luminaires each located on the stadium and with a desired aiming location or point on the pitch to attempt to provide a suitable lighting effect. The light designer may create such a light plan remotely, e.g. by employing illumination simulations for the area to be illuminated, which simulations may yield the light plan to be implemented.
Such a light plan is typically used by an illumination system installer to install the luminaires in their relative positions and to aim the luminaires in accordance with the provided aiming information. This however is not without problems. For example, the installer may have difficulty in correctly aiming the luminaires, for instance because of a lack of a clear reference on the area to aim at. From the luminaire location, the installer has a clear overview of the field but it is very difficult to accurately determine the aiming location in the field.
To improve the accuracy of the alignment procedure, the installer can use a grid created by manually putting visual markers on the area to be illuminated at the required coordinates and a laser pointer aligned with the luminaire optical axis. In such a way the alignment is a matter of aiming the laser spot at the requested visually interpolated locations on the grid. However, the placement of the visual markers on the area is an elaborate task and the alignment itself based on the laser spot is prone to errors. Moreover, such a procedure is less suitable for vertical areas, e.g. façades. In addition, the installer may find that a particular luminaire cannot be aimed at the desired area location because of an obstacle in the light path of the luminaire that the light designer was unaware of when (remotely) deciding the mounting positions for the luminaire or because the intended mounting location of the luminaire is unavailable, in which case the installer usually mounts the luminaire in the nearest available location. In this scenario, the provided light plan is imperfect such that the installer cannot achieve the predefined illumination pattern even when perfectly implementing the provided light plan.
These problems can lead to the resulting actual illumination pattern on the area deviating from the predefined illumination pattern, e.g. containing excessive inhomogeneities, such that some adjustment of the luminaire arrangement is required.
US published application US 2013/0268246 suggests to attach a camera to the luminaire so that the installer is able to ‘see’ where the light from the luminaire will be directed by producing a ‘cropped’ image reflecting the modelled light pattern. This cropped image can then be compared with a further ‘wide-angle’ camera image to determine the location of the light beam and pattern relative to a wide-angle image and so determine whether the luminaire is directed at the required direction. Although this can improve the aiming accuracy of the luminaire installation, it for instance does not assist the installer when encountering obstacles in the light path of the luminaires.